The design of modern computer system and telecommunications equipment has moved from proprietary vender-specific solutions to standardized platforms designed for expansion, flexibility, and scalability. For example, a typical telecom switch employs a chassis housing multiple modular switching boards that are connected to a backplane or midplane. Similarly, many new computer server deployments use blade servers, which include multiple server blades (cards) coupled to a backplane or midplane in a chassis. Under the standardized approach, boards and cards from different vendors can be employed in the same system with guaranteed interoperability.
In parallel with the rapid increase in processor performance observed in the past decade has been an increase in system complexity. In particular, the number and density of input/output (I/O) signals in telecom systems and blade servers have significantly increased. Furthermore, the bandwidth of the I/O signal lines is now typically specified in 100's of Megahertz or even gigahertz (GHz) levels for serial interconnect technologies such as PCI Express and Advanced Switching. This leads to very strict mechanical tolerance and alignment requirements for the connectors that are used to couple signals between a board or card and the system's backplane or midplane.
A typical expansion board or card for these types of environments employs one or more pinned connectors, each of which includes multiple rows (typically) of pins arrayed in a grid. As an option, a board/card edge connector may be used. Meanwhile, a mating connector is provided on the backplane or midplane. Upon insertion of the board/card in the chassis, the connectors are coupled.
The expansion board/card insertion process is often assisted by two means: chassis slots and insertion/ejection mechanisms. A typical chassis slot provides a pair of guide rails that is adapted to slidingly engage parallel board edges during insertion or extraction of the board. Meanwhile, the insertion function of the insertion/ejection mechanism urges the board forward so as to engage the connectors in a proper manner. Similarly, the ejection function of the insertion/ejection mechanism is used to cause the board to be disconnected from the connectors in a controller manner.